Two days in a row this weekend, Washington, D.C., hit 100 degrees. Overnight lows didn’t drop below 80 degrees for three straight days.

Record temperatures mounted at observing sites in the region, both for scorching daytime temperatures and unusually warm nights.

The humidity made these high temperatures feel even more uncomfortable. The dew point, which is one measure of how much moisture is in the air, has been around or well above 70 degrees since the middle of last week. Dew points below 60 degrees are considered “low humidity.” Even up to 65 degrees, conditions are tolerable. On Saturday, it surged to an obscene 78 degrees in D.C.

Combined, the heat and the humidity led to maximum heat index levels of 110-120 degrees.

Things didn’t cool off at night. The District posted its 5th, 6th and 7th nights this summer with lows remaining 80 degrees or higher, tied for the most on record with 2011. The lows of 81 degrees on Friday and Saturday matched the warmest on record for the month of August. The temperature finally dipped into the upper 70s on Monday morning.

Through Sunday, D.C. has had 38 90-degree days in 2016, which is about eight days more than average for this point in the year.

It’s now the fourth hottest meteorological summer — June through August — in D.C. since records began in 1871, the National Weather Service says. Five of the six hottest summers have occurred since 2010.

(Ian Livingston/Capital Weather Gang)

Friday

Washington, D.C., hit a high temperature of 99 degrees, which tied the record high for the date set in 1926. Baltimore, which measures its official temperature at BWI, set a new record for the warmest minimum temperature, 79 degrees, which broke the record of 78 degrees set in 1926. Dulles tied its record warmest minimum of 75 degrees, first set in 1988.

Saturday

On Saturday, Washington, D.C., soared to 101 degrees and tied the record high for the date, originally set in 1881. Dulles hit 99 degrees, which broke the old record of 98 set in 2002. The airport also only managed to get down to 78 degrees on Friday morning, which broke the old record warm minimum of 76 set in 1988.

Sunday

Washington, D.C., hit 100 degrees and tied the record from 1943. It was also the first time D.C. hit 100 degrees on back-to-back days in August since 1997. Dulles reported a record warm minimum of 76 degrees, which broke the record of 75 last set in 2005.

Records for Washington, D.C., go back to 1872, for Dulles to 1962 and for Baltimore to 1870.

Angela FritzAngela Fritz is an atmospheric scientist and The Washington Post's deputy weather editor. Before joining The Post, Fritz worked as a meteorologist at CNN in Atlanta and Weather Underground in San Francisco. She has a BS in meteorology and an MS in earth and atmospheric science. Follow